3ltr twincam engine, coming together
#212
Drifting
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For some reason my recollection was that the new headstuds were an improvement in terms of track days vs headgasket replacement. I certainly agree that the Cometics are the way to go if you drive to and from the track...especially if the track is miles away. Being towed from Wakefield Park is noooo fun!
The ARP studs has a psi rating of 200 000 only 20% higher than the original ones. Maybe the thread flex or the clamping area of the nut is to smale? It could also be the block twisting and an upgrade of the girdle bolts combined with the larger head studs will do the trick?
I have a 1.5 hour drive to the closest track and being towed home is not realy an option...
I have a 1.5 hour drive to the closest track and being towed home is not realy an option...
Yes, Stock head studs and torque.
Interesting reference about head studs
http://www.heritagemotorcar.com/research/index.htm
http://www.heritagemotorcar.com/research/index.htm
http://www.heritagemotorcar.com/research/index.htm
http://www.heritagemotorcar.com/research/index.htm
Sean
#214
Drifting
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Sorry Sid,
Missed that one. hopefully soon, western sydney international drag way have wednesday night drags. It only cost $50 or so and you get about 5 runs if you get there by 3. Its quite a long wait but you get to check out the other cars in the line ups.
Missed that one. hopefully soon, western sydney international drag way have wednesday night drags. It only cost $50 or so and you get about 5 runs if you get there by 3. Its quite a long wait but you get to check out the other cars in the line ups.
#215
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Just don't tell Bruce..heheheh...
Yes, that's right on the torquing. When we went to the higher tq rate we got a better longevity.
Yes, that's right on the torquing. When we went to the higher tq rate we got a better longevity.
#216
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Sean - What you have accomplished with these cars is amazing and inspiring. Thanks for sharing your projects here. I have read everyone of your threads. ![thumbup](https://rennlist.com/forums/graemlins/thumbup.gif)
According to Cometic, this kind of damage is the result of head lift/flex that overworks the seal boss and then a fatigue fracture occurs and starts to propagate. Some refer to this a "chomping". I think the math will show that head/block flex is the greatest at cylinders 2 and 3. I do think that ARP studs and higher torque will help some but that much of what occurs is the result of high peak cylinder pressure (22psi) and the large bore size in our motors. I have been researching this extensively for my own build. Fatigue failure is fairly repeatable and thus the consistency you have experienced.
Also, I believe in general that HG failures on cylinder 4 are more related to detonation (4 getting the least cooling) rather than flex. Obviously detonation has not been an issue for your car with relatively low CR and E85.
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According to Cometic, this kind of damage is the result of head lift/flex that overworks the seal boss and then a fatigue fracture occurs and starts to propagate. Some refer to this a "chomping". I think the math will show that head/block flex is the greatest at cylinders 2 and 3. I do think that ARP studs and higher torque will help some but that much of what occurs is the result of high peak cylinder pressure (22psi) and the large bore size in our motors. I have been researching this extensively for my own build. Fatigue failure is fairly repeatable and thus the consistency you have experienced.
Also, I believe in general that HG failures on cylinder 4 are more related to detonation (4 getting the least cooling) rather than flex. Obviously detonation has not been an issue for your car with relatively low CR and E85.
#217
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Shawn I’d assume that we’d see consistent peppering on #4 if that were the case? Not sure that we’ve seen any overt signs of detonation? How about you guys?
I think Sean’s new build with the 3L block and Siamesed bores has to be better in this regard. The possible loss of cooling is a secondary matter. I am hoping the line bored, pinned girdle and deckplated block will help me in these h/g matters. Sean is opening that motor up next week for a new h/g just as a precaution and perhaps the main bearings before it will finally go back into the car. I shall report back findings on this motor.
Overall, it’s great to see some of us are working away at this achilles heel of our cars.
I think Sean’s new build with the 3L block and Siamesed bores has to be better in this regard. The possible loss of cooling is a secondary matter. I am hoping the line bored, pinned girdle and deckplated block will help me in these h/g matters. Sean is opening that motor up next week for a new h/g just as a precaution and perhaps the main bearings before it will finally go back into the car. I shall report back findings on this motor.
Overall, it’s great to see some of us are working away at this achilles heel of our cars.
#218
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Shawn I’d assume that we’d see consistent peppering on #4 if that were the case? Not sure that we’ve seen any overt signs of detonation? How about you guys?
I think Sean’s new build with the 3L block and Siamesed bores has to be better in this regard. The possible loss of cooling is a secondary matter. I am hoping the line bored, pinned girdle and deckplated block will help me in these h/g matters. Sean is opening that motor up next week for a new h/g just as a precaution and perhaps the main bearings before it will finally go back into the car. I shall report back findings on this motor.
Overall, it’s great to see some of us are working away at this achilles heel of our cars.
I think Sean’s new build with the 3L block and Siamesed bores has to be better in this regard. The possible loss of cooling is a secondary matter. I am hoping the line bored, pinned girdle and deckplated block will help me in these h/g matters. Sean is opening that motor up next week for a new h/g just as a precaution and perhaps the main bearings before it will finally go back into the car. I shall report back findings on this motor.
Overall, it’s great to see some of us are working away at this achilles heel of our cars.
"Shawn I’d assume that we’d see consistent peppering on #4 if that were the case?" Have most of the failures you have seen with E85 been on cylinder 4?
#219
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I havnt seen any sign of detonation. I think we are also experiencing a problem with the studs being so far from the bores.
I have had better luck with filling the block, however, I pulled the head 3/4 through the season last year and saw the thin gasket on the bottom side starting to split. Mine was dead center of the bore. Right where the gasket is embossed.
I am going to see if cometic will do a gasket for me without the embossing. Or see if I could get away with deleting the lower thin gasket and just copper spray the thick one.
Any way you look at it, for the horsepower and how many miles I put on it, I think it was great.
Dave Novak will be showing something completely different soon. I am looking forward to this!! If it works out well I could see a huge increase in boost pressure.
I have had better luck with filling the block, however, I pulled the head 3/4 through the season last year and saw the thin gasket on the bottom side starting to split. Mine was dead center of the bore. Right where the gasket is embossed.
I am going to see if cometic will do a gasket for me without the embossing. Or see if I could get away with deleting the lower thin gasket and just copper spray the thick one.
Any way you look at it, for the horsepower and how many miles I put on it, I think it was great.
Dave Novak will be showing something completely different soon. I am looking forward to this!! If it works out well I could see a huge increase in boost pressure.
#220
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I havnt seen any sign of detonation. I think we are also experiencing a problem with the studs being so far from the bores.
I have had better luck with filling the block, however, I pulled the head 3/4 through the season last year and saw the thin gasket on the bottom side starting to split. Mine was dead center of the bore. Right where the gasket is embossed.
I am going to see if cometic will do a gasket for me without the embossing. Or see if I could get away with deleting the lower thin gasket and just copper spray the thick one.
Any way you look at it, for the horsepower and how many miles I put on it, I think it was great.
Dave Novak will be showing something completely different soon. I am looking forward to this!! If it works out well I could see a huge increase in boost pressure.
I have had better luck with filling the block, however, I pulled the head 3/4 through the season last year and saw the thin gasket on the bottom side starting to split. Mine was dead center of the bore. Right where the gasket is embossed.
I am going to see if cometic will do a gasket for me without the embossing. Or see if I could get away with deleting the lower thin gasket and just copper spray the thick one.
Any way you look at it, for the horsepower and how many miles I put on it, I think it was great.
Dave Novak will be showing something completely different soon. I am looking forward to this!! If it works out well I could see a huge increase in boost pressure.
What cylinder did you get the fracture on?
#221
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I am certainly not an expert in these areas. I have been researching this and looking at trends under various conditions. I see understanding this as key to my own builds success. Not exactly sure what you mean by this:
"Shawn I’d assume that we’d see consistent peppering on #4 if that were the case?" Have most of the failures you have seen with E85 been on cylinder 4?
"Shawn I’d assume that we’d see consistent peppering on #4 if that were the case?" Have most of the failures you have seen with E85 been on cylinder 4?
I havnt seen any sign of detonation. I think we are also experiencing a problem with the studs being so far from the bores.
I have had better luck with filling the block, however, I pulled the head 3/4 through the season last year and saw the thin gasket on the bottom side starting to split. Mine was dead center of the bore. Right where the gasket is embossed.
I am going to see if cometic will do a gasket for me without the embossing. Or see if I could get away with deleting the lower thin gasket and just copper spray the thick one.
Any way you look at it, for the horsepower and how many miles I put on it, I think it was great.
Dave Novak will be showing something completely different soon. I am looking forward to this!! If it works out well I could see a huge increase in boost pressure.
I have had better luck with filling the block, however, I pulled the head 3/4 through the season last year and saw the thin gasket on the bottom side starting to split. Mine was dead center of the bore. Right where the gasket is embossed.
I am going to see if cometic will do a gasket for me without the embossing. Or see if I could get away with deleting the lower thin gasket and just copper spray the thick one.
Any way you look at it, for the horsepower and how many miles I put on it, I think it was great.
Dave Novak will be showing something completely different soon. I am looking forward to this!! If it works out well I could see a huge increase in boost pressure.
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Is Dave proposing something gasket-wise or a totally new way of buttoning up the system overall?
#222
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Dave is trying something completely different.
#223
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#224
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Just getting the gasket a little further out from the cylinder. As you know, the 103mm is very close to protruding into the cylinder. Just a boring mod.
#225
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Interestingly Sean was mentioning the 'embossing' on the normal Cometics. Keep us in the loop should you succeed in getting them to make some.